The 56-year-old said women of her age felt "invisible" and those involved in casting were unsure what to do with them if they were not "kooky".
The former New Tricks actress said she sometimes watched TV to spot roles which she could play -- based on the right age range rather than whether she would actually want them - but found "there's consistently nothing.
"Emma Thompson is probably the only person I can think of who's my age and working and she's had to write stuff for herself."
Redman - soon to appear in a Tommy Cooper biopic on ITV called Not Like That, Like this - said she had pitched an autobiographical story to television chiefs about a woman approaching the menopause whose children were flying the nest.
"They wouldn't touch it because they thought it was not something that men would want to watch, which is a shame because a lot of it's very funny," she said.
She was also rejected when she said she took a story written by comic Jenny Eclair to ITV. "They said 'your character is too unsympathetic'. God, I was so angry," she added.